research article experimental investigation on an...

Hindawi Publishing CorporationInternational Journal of PhotoenergyVolume 2013, Article ID 490124, 6 pageshttp://dx.doi.org/10.1155/2013/490124

Research ArticleExperimental Investigation on an Absorption RefrigeratorDriven by Solar Cells

Zi-Jie Chien,1 Hung-Pin Cho,2 Ching-Song Jwo,1 Chao-Chun Chien,1

Sih-Li Chen,2 and Yen-Lin Chen3

1 Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology,Taipei 10608, Taiwan

2Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan3Department of Computer Science and Information Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

Correspondence should be addressed to Yen-Lin Chen; [email protected]

Received 23 November 2012; Accepted 7 January 2013

Academic Editor: Ho Chang

Copyright © 2013 Zi-Jie Chien et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

This experiment is to study an absorption refrigerator driven by solar cells. Hand-held or carried in vehicle can be powered by solarenergy in places without power. In the evenings or rainy days, it is powered by storage battery, and it can be directly powered byalternating current (AC) power supply if available, and the storage battery can be charged full as a backup supply. The proposedsystem was tested by the alternation of solar irradiance 550 to 700W/m2 as solar energy and 500ml ambient temperature water ascooling load. After 160minutes, the proposal refrigerator canmaintain the temperature at 5–8∘C, and the coefficient of performance(COP) of NH

3-H2O absorption refrigeration system is about 0.25.Therefore, this system can be expected to be used in remote areas

for refrigeration of food and beverages in outdoor activities in remote and desert areas or long-distance road transportation of foodor low temperature refrigeration of vaccine to avoid the deterioration of the food or the vaccines.

1. Introduction

Nowadays the economic development has resulted in a lotof energy exploitation, and the oil reservation becomesexhausted. It will run out within less than 50 years, caus-ing the so-called energy crisis. Overexploitation has alsocaused increasingly serious global warming problem. Manyadvanced countries in the world today take the lead in pro-moting the research and development of alternative energysuch as wind energy, solar energy, and biomass energy. Theimportance of research and development on green energyhas attracted much attention. Although their cost is high,continuous research and development will achieve the stable,easy-to-use, and reasonably priced alternative energy in someday. This is a road we must take for the survival of humanity.

In literature, there are numerous studies in absorptionrefrigerators. Bansal and Martin [1] have compared the per-formance of vapor compression and thermoelectric andabsorption refrigerators. Dai et al. [2] have experimentalinvestigation on a thermoelectric refrigerator driven by solar

cells. Riffat and Qiu [3] conducted comparative investiga-tion of thermoelectric airconditioners versus vapor com-pression and absorption airconditioners. Fernandez-Searaand Vazquez [4] develop control algorithm of the optimalgeneration temperature NH

3-H2O absorption refrigeration

systems. Goktun andDeha Er [5] utilize a solar-assisted com-bined absorption-vapor compression system for air condi-tioning and space heating.Wu et al. [6] propose optimizationsolar absorption refrigerator. One of the most promisingschemes is the utilization of an absorption refrigeration cyclewith solar energy serving as the source of heat to operate thegenerator. Yaxiu et al. [7] conduct experimental research ona new solar pump-free lithium bromide absorption refrigera-tion systemwith a second generator themaximum coefficientof performance (COP) approaches 0.787. Hwang [8] poten-tial energy benefits of integrated refrigeration system withmicroturbine and absorption chiller. Fathi et al. [9] researchan irreversible thermodynamic model for solar absorptionrefrigerator. Sencan [10] uses artificial neural networks per-formance of ammonia-water refrigeration systems.

2 International Journal of Photoenergy

A

HH

A

WAA W

A

Rectifier Storage battery

Door

Gripe

Controller

Bracket

Battery

Solar cell

Shell

Foot

Condenser Evaporator

Liquid seal

Liquid seal

AbsorptionGeneratorAC

power

5∼8∘C

30∘C

80∘C

Separator

Figure 1: Experimental equipment of absorption refrigerator.

AL-Hawaj and AL-Mutairi [11] cogeneration schemecomprising a combined cycle power plant (CCPP) withan absorption chiller used for space cooling is studied.Sieres and Fernandez-Seara [12] experimental investigationof mass transfer performance with some random packingsfor ammonia rectification in ammonia-water absorption.Sozen et al. [13–15] have improved performance of absorptionrefrigeration system by using triple-pressure level. Said et al.[16, 17] indicate that continuously operating solar-poweredaqua-ammonia absorption system with refrigerant storageis the most suitable alternative design for an uninterruptedsupply of cooling effect. Rothwell et al. [18, 19] developeda coupled solar wing-magnetosphere-ionosphere model fordetermining the ionospheric penetration electric field. Bilgili[20] has conducted hourly simulation and performanceof solar electron-vapor compression refrigeration system.Colonna and Gabrielli [21] used a new solar pump-freelithium bromide absorption refrigeration system with asecond generator. Odeh [22] proposed a unified model ofsolar thermal electric generation systems. Al-Alili et al. [23,24] use a solar powered absorption cycle under Abu Dhabi’sweather conditions. Monne et al. [25] developed a stationaryanalysis of a solar LiBr–H

2O absorption refrigeration system.

Alvares and Trepp [26] developed a simulation of a solardriven aqua-ammonia absorption refrigeration system part 1:mathematical description and system optimization. LeBreuxet al. [27] proposed a controlmethod of a hybrid solar/electricthermal energy storage system.

In summary of the previously mentioned literaturereview, the proposed small-scale absorption refrigeration sys-tem driven by solar power is unprecedented. This studyproposes an absorption refrigeration system using refrigerant

NH3and absorbent H

2O. As being an environmentally

friendly refrigeration system, it is powered by solar cells. Thesuccessful development of the proposed system can solveproblems such as the long-distance transportation of medicalvaccines and the refrigeration of food and beverages inremote areas lacking power supply.

2. Experiment and Methodology

2.1.The Proposed Experimental System. As shown in Figure 1,the energy of the absorption refrigeration is supported by18V of direct electricity from solar cells and the capacity ofcold storage covers in 30 liters. Power consumption covers1.2 KWH/24 h with filling 70 grams of NH

3refrigerant. The

experimental system is the NH3-H2O absorption refriger-

ation system consisting of solar cells, controller, storagebattery, rectifier, and absorption refrigerator. In the daytime,the solar cells receive solar energy to power the absorptionrefrigerator. When too much energy is supplied, the con-troller will store the excess energy in the storage battery.When the solar power is insufficient or unavailable at nightor in cloudy days, it depends on the storage battery for powersupply. The storage battery can be charged in places with ACpower supply as a backup power source. In order to achievebetter power generation efficiency of the solar panel, it willalways be placed towards the sun. The shape between solarpanel and horizontal line becomes tilt angle. The optimalangle for tilted surface was calculated by searching for thevalues of which the daily total solar radiation was at amaximum for a specific period. The yearly average optimaltilt angles for a south-facing solar collector about 31.21 to34.31 degrees [28]. Therefore, the tilt angle of the study isdetermined as 35∘C.

International Journal of Photoenergy 3

H

A

W

RectifierStorage battery

Condenser

Evaporator

Liquid seal

Liquid seal

AbsorptionGenerator

Separator

Insulationlayer

Temperature.sensor

Current transducer

Solar cell

Data logger

Computer

ab

c

def

gh

Door

Solar irradiatemeter

ControllerA

H

A

AC power

Gripe

Water AC

DC18 v65 w

65 w220 v

A+WA+W

5∼8∘C

30∘C

80∘C

Figure 2: Distribution of various measurement points of the experimental system.

Table 1: Specifications of solar cell driven absorption refrigerator.

Items Description Value

Array of solar cell

The area of solar cell, 𝐴 1.78m−2

Max output power of solar cell, 𝑃max 184WSolar irradiance, 𝑆 800Wm−2

The efficiency of energy conversion from solar energy to electric power 0.14

Storage battery

Stands for the battery storage capacity 100AHElectric consumption 22AH/dayThe number of day without sunshine 2 daysThe maximum degree of electric discharge 0.8The efficiency of the storage battery 0.86The loss coefficient of the circuit 0.05The correction coefficient of temperature 0.9

Absorption refrigeratorRefrigerant NH3

Absorption H2OPower 65W, 17V

2.2. The Proposed Experimental Method and Procedures. Thelocation of installation of various measurement points, dataacquisition device, and personal computer connection of theexperimental system are shown in Figure 2.We applied a datalogger and a computer to collect six points of data that setsample time to two minutes. These six points include fourtemperatures points (i.e., ambient temperature, generatortemperature, cooled side temperature, and water tempera-ture), one current of solar cell, and one solar irradiate.

We conduct the no-load test at first and then the loadedtests while gradually recording the experimental results. Themajor test of this study is to test the performance andfeasibility of running the absorption refrigeration system byusing the power generated by solar cells during the day.

Regarding the backup battery power supply performanceand the charging system’s material characteristics are notdiscussed in this study.

The experimental system’s solar cells and storage battery,absorption refrigerator specifications are shown in Table 1.The maximum power capacity of the solar cells is 184W. Themaximum storage capacity of the storage cell is 100Ah. Therefrigerant of the absorption refrigeration system is NH

3and

the absorbent is H2O.The input power voltage is 17 V, and the

input power is 65W.

3. Theoretical Formulation for TransformerThe performance of the solar cells and absorption refrigera-tion system can be obtained by the following equation.


10

0

25

35

10 20 30 40 50 60 70 80 90 1000

5

20

30

40

Time (min)

Cold side temperatureAmbient temperature

Tem

pera

ture

(∘C)

Figure 3: The changes in the ambient temperature and cold sidetemperature under sunlight.

The output of power supply capacity of solar cells [2] iscalculated by the following equation:

𝑃solar = 𝑆𝐴𝜂𝑃𝑉, (1)

where 𝑃solar is power supply capacity of solar cells (W), S issolar irradiance (W/m2),A is the area of Solar array to receivesolar irradiation (m2), and 𝜂

𝑃𝑉is the efficiency of energy

conversion from solar energy to electric power.According (1), the power generation of the solar panel is

proportional to the solar irradiance.The coefficient of performance (COP) of absorption

refrigeration system [3] is

COP = Desired outputRequired input

=𝑄𝐿

𝑄gen= (1 −𝑇𝑎

𝑇𝑔

)(𝑇𝑟

𝑇𝑎− 𝑇𝑟

) ,

(2)

where𝑄gen is heat energy given to the generator in absorption(W), 𝑄

𝐿is heat energy that evaporator absorbs from the

cooled space (W), 𝑇𝑎is the ambient temperature (K), 𝑇

𝑔

is the generator temperature (K), and 𝑇𝑟is the cooled side

temperature (K).We could get several trends from (2); namely, as 𝑇

𝑔

increases, the COP increases; as 𝑇𝑟increases, the COP

increases; as 𝑇𝑎increases, the COP decreases.

4. Results and Discussion

In the no-load test of the absorption refrigeration system,we conducted the 100-minute experimental test and recordthe experimental results in Figures 3–5 before carrying outthe 200-minute loaded experimental test. The test resultswere recorded in Figures 6–8, and the theoretical relationshipequations were applied for analysis to get the following:

Under the sun, the ambient temperature is 30∘C, and thecold side temperature is 24∘C. The trend of cold side tem-perature is shown in Figure 3. When solar panels are underthe sunlight, the absorption refrigeration system will start to

Time (min)

Out

put

volta

ge (V

)

Output voltageSolar irradiance

010 20 30 40 50 60 70 80 90 1000

16.8 16.9

17 17.1 17.2 17.3 17.4 17.5 17.6

760

780

800

820

860

880

900

Sola

r irr

adia

nce (

W/m

2)

Figure 4: The changes in solar irradiance and output voltage undersunlight.

Time (min)

COP

COP

0.210 20 30 40 50 60 70 80 90 1000

0.3

0.4

0.5

0.6

0.7

0.8

30

40

50

60

70

20

𝑄𝐶

𝑄𝐶

(W)

Figure 5:The changes in refrigeration systemCOPand refrigeratingcapacity 𝑄

𝐶, under the sunlight.

run. It can be apparently found that the cold side temperatureslowly decreases. After running for 30 minutes, the cold sidetemperature dropped to 10∘C. After 70-minute running, thecold side temperature dropped to 5∘C.

As shown in Figure 4, due to changes in solar irradiance,the power supply 880W/m2 dropped to 770W/m2 after 90minutes.The solar panel output voltage remains between 16.9and 17.5 V. At the moment of 35 minutes, the sunlight coveredby clouds leads to the deep drop of voltage. However, toreveal the real experimental situation, we still keep these dataunaltered in Figure 4.

As shown in Figure 5, when the ambient temperatureremains unchanged, the cold side temperature dramaticallydropped to below 5∘C after running for 70 minutes. Dueto the decrease in cold side temperature, the absorptionrefrigeration system COP dropped from 0.5 to 0.28, therefrigeration system cooling capacity dropped from 69Wto 39W, proving that the cooling capacity will decreaseover declining cold side temperature and its COP will alsodecrease.

International Journal of Photoenergy 5

10

15

0

25

20 40 60 80 200180100 120 140 1600

5

20

30

Time (min)

Cold side temperatureWater temperatureAmbient temperature

Tem

pera

ture

(∘C)

Figure 6: The changes in the temperature of 500mL water placedinside, under the sunlight.

The loaded test was to place the 500mL room temper-ature water inside as shown in Figure 6. When the testingambient temperature was 27∘C, the cold side temperatureslowly dropped to 24∘C. After running for 20 minutes, thecold side temperature dropped to 13∘C, after running for100 minutes, the cold side temperature dropped to 5∘C. Thewater temperature dropped very slowly from the beginningtemperature of 24∘C. After 80minutes, the water temperatureapparently dropped. After 200 minutes, the water tempera-ture dropped to 8∘C and would be even lower if the systemwas still running on.

The study investigates the alternation of solar irradiancemeasured every two minutes while driving on the high way,which results in a sudden transform of solar irradiance. Thesolar irradiance and output voltage changes are shown inFigure 7. When the solar irradiance is 550 to 700W/m2, theoutput voltage is about 16 to 17.2 V. In other words, when thesolar irradiance rate is greater, the solar power generationwill be greater. According to (1), the power generation of thesolar panel is proportional to the solar irradiance.The resultsconfirm the phenomenon given in (1).

As shown in Figure 8, under the sunlight, 500mL waterof room temperature is placed inside. At 0–60minutes, watertemperature from 24 to 21∘C, and cold side temperature from24 to 8∘C as shown in Figure 6, cooling load is high. COPdrops rapidly from 0.38 to 0.22, and the refrigerating capacitydrops rapidly from 65 to 48W. At 60–160 minutes, watertemperature from 21 to 12∘C, and cold side temperature from8 to 5∘C mean cooling load decreases but it is still high, thesystem COP is around 0.22 and the refrigerating capacityis about 45W. At 160–200 minutes, the water temperaturefrom 12∘C to 10∘C, and cold side temperature of 5∘C, meancooling load is low as shown in Figure 6 and the system COPincreases from 0.22 to 0.28.

Time (min)

Out

put

volta

ge (V

)

Output voltageSolar irradiance

20 40 60 80 120 140 160 180 200100013

14

15

16

17

18

19

400

450

500

550

600

650

700

Sola

r irr

adia

nce (

W/m

2)

Figure 7: The changes in output voltage and solar irradiance, when500mL was placed inside, under the sunlight.

Time (min)

COP

COP

30

40

50

60

70

80

90

100

110

20 40 60 80 120 140 160 180 2001000

0

0.1

0.2

0.3

0.4

−0.2

−0.1

𝑄𝐶

𝑄𝐶

(W)

Figure 8:The changes in refrigeration systemCOPand refrigeratingcapacity 𝑄

𝐶, when 500mL water of room temperature is placed

inside, under the sunlight.

5. Conclusions

In summary of the experimental research results, the solarenergy can supply energy for the running of the absorp-tion refrigerator. The outdoor activities and works, such asmineral development, road construction, and other occa-sions, can be adopted. It is designed in order to meet theoutdoor usage requirements as lightweight, low price, andday and night usage. According to the experimental results,the alternation of solar irradiance 550 to 700W/m2 and500mL ambient temperature water as cooling load. After160 minutes, the proposal refrigerator can maintain thetemperature at 5–8∘C, and the COP is about 0.25.


Acknowledgments

This project is financially sponsored by the National ScienceCouncil under Grants NSC-101-2622-E-027-025-CC3, NSC-101-2219-E-027-006, and NSC-99-2221-E-027-069-MY3 andFumin Education Foundation.

References

[1] P. K. Bansal and A.Martin, “Comparative study of vapour com-pression, thermoelectric and absorption refrigerators,” Interna-tional Journal of Energy Research, vol. 24, no. 2, pp. 93–107, 2000.

[2] Y. J. Dai, R. Z. Wang, and L. Ni, “Experimental investigation ona thermoelectric refrigerator driven by solar cells,” RenewableEnergy, vol. 28, no. 6, pp. 949–959, 2003.

[3] S. B. Riffat and G. Qiu, “Comparative investigation of ther-moelectric air-conditioners versus vapour compression andabsorption air-conditioners,” Applied Thermal Engineering, vol.24, no. 14-15, pp. 1979–1993, 2004.

[4] J. Fernandez-Seara and M. Vazquez, “Study and control ofthe optimal generation temperature in NH

3–H2O absorption

refrigeration systems,” AppliedThermal Engineering, vol. 21, pp.343–353, 2001.

[5] S. Goktun and I. Deha Er, “The optimum performance of asolar-assisted combined absorption-vapor compression systemfor air conditioning and space heating,” Solar Energy, vol. 71, no.3, pp. 213–216, 2001.

[6] C. Wu, L. Chen, and F. Sun, “Optimization of solar absorptionrefrigerator,”AppliedThermal Engineering, vol. 17, no. 2, pp. 203–208, 1997.

[7] G. Yaxiu, W. Yuyuan, and K. Xin, “Experimental research on anew solar pump-free lithium bromide absorption refrigerationsystem with a second generator,” Solar Energy, vol. 82, no. 1, pp.33–42, 2008.

[8] Y. Hwang, “Potential energy benefits of integrated refrigerationsystem with microturbine and absorption chiller,” InternationalJournal of Refrigeration, vol. 27, no. 8, pp. 816–829, 2004.

[9] R. Fathi, C. Guemimi, and S. Ouaskit, “An irreversible ther-modynamicmodel for solar absorption refrigerator,”RenewableEnergy, vol. 29, no. 8, pp. 1349–1365, 2004.

[10] A. Sencan, “Performance of ammonia-water refrigeration sys-tems using artificial neural networks,” Renewable Energy, vol.32, no. 2, pp. 314–328, 2007.

[11] O. M. AL-Hawaj and H. AL-Mutairi, “A combined power cyclewith absorption air conditioning,”Energy, vol. 32, no. 6, pp. 971–982, 2007.

[12] J. Sieres and J. Fernandez-Seara, “Experimental investigationof mass transfer performance with some random packings forammonia rectification in ammonia-water absorption refrigera-tion systems,” International Journal of Thermal Sciences, vol. 46,no. 7, pp. 699–706, 2007.

[13] A. Sozen and M. Ozalp, “Performance improvement of absorp-tion refrigeration system using triple-pressure-level,” AppliedThermal Engineering, vol. 23, no. 13, pp. 1577–1593, 2003.

[14] Y. He and G. Chen, “Experimental study on an absorptionrefrigeration system at low temperatures,” International Journalof Thermal Sciences, vol. 46, no. 3, pp. 294–299, 2007.

[15] J. V. C. Vargas, J. C. Ordonez, E. Dilay, and J. A. R. Parise, “Mod-eling, simulation and optimization of a solar collector drivenwater heating and absorption cooling plant,” Solar Energy, vol.83, no. 8, pp. 1232–1244, 2009.

[16] G. Pei, J. Li, and J. Ji, “Analysis of low temperature solar thermalelectric generation using regenerative organic rankine cycle,”Applied Thermal Engineering, vol. 30, no. 8-9, pp. 998–1004,2010.

[17] S. A. M. Said, M. A. I. El-Shaarawi, and M. U. Siddiqui, “Alter-native designs for a 24-h operating solar-powered absorptionrefrigeration technology,” International Journal of Refrigeration,vol. 35, no. 7, pp. 1967–1977, 2012.

[18] P. L. Rothwell and J. R. Jasperse, “A coupled solar wind-magnetosphere-ionosphere model for determining the iono-spheric penetration electric field,” Journal of Atmospheric andSolar-Terrestrial Physics, vol. 69, no. 10-11, pp. 1127–1134, 2007.

[19] N. Molero-Villar, J. M. Cejudo-Lopez, F. Domınguez-Munoz,and A. Carrillo-Andres, “A comparison of solar absorptionsystem configurations,” Solar Energy, vol. 86, no. 1, pp. 242–252,2012.

[20] M. Bilgili, “Hourly simulation and performance of solar elec-tric-vapor compression refrigeration system,” Solar Energy, vol.85, no. 11, pp. 2720–2731, 2011.

[21] P. Colonna and S. Gabrielli, “Industrial trigeneration using am-monia-water absorption refrigeration systems (AAR),” AppliedThermal Engineering, vol. 23, no. 4, pp. 381–396, 2003.

[22] S. D. Odeh, “Unified model of solar thermal electric generationsystems,” Renewable Energy, vol. 28, no. 5, pp. 755–767, 2003.

[23] A. Al-Alili, Y. Hwang, R. Radermacher, and I. Kubo, “Optimiza-tion of a solar powered absorption cycle under Abu Dhabi’sweather conditions,” Solar Energy, vol. 84, no. 12, pp. 2034–2040, 2010.

[24] A. Lecuona, R. Ventas, M. Venegas, A. Zacarıas, and R. Salgado,“Optimum hot water temperature for absorption solar cooling,”Solar Energy, vol. 83, no. 10, pp. 1806–1814, 2009.

[25] C. Monne, S. Alonso, F. Palacın, and J. Guallar, “Stationaryanalysis of a solar LiBr–H

2O absorption refrigeration system,”

International Journal of Refrigeration, vol. 34, no. 2, pp. 518–526,2011.

[26] S. G. Alvares and C. Trepp, “Simulation of a solar driven aqua-ammonia absorption refrigeration system—part 1: mathemati-cal description and system optimization,” International Journalof Refrigeration, vol. 10, no. 1, pp. 40–48, 1987.

[27] M. LeBreux, M. Lacroix, and G. Lachiver, “Control of a hybridsolar/electric thermal energy storage system,” InternationalJournal of Thermal Sciences, vol. 48, no. 3, pp. 645–654, 2009.

[28] K. Bakirc, “General models for optimum tilt angles of solarpanels: Turkey case study,” Renewable and Sustainable EnergyReviews, vol. 16, no. 8, pp. 6149–6159, 2012.

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